Fluid damped bushings are used in automotive suspension and power train applications to improve the noise, vibration and handling characteristics of the automotive vehicle. Typically, such a fluid damped bushing has an inner metal sleeve to which is bonded an elastomeric, resilient member. The annular member has a spaced apart pair of recesses in its outer surface, and the recesses are interconnected by a flow passage that has a high resistance to flow. The resilient member is then surrounded by an outer metal sleeve which seals the recesses and the flow passage of the resilient member.
A fluid damped bushing of the foregoing type typically requires that an intermediate sleeve, known as a window metal, be inserted between the resilient member and the outer sleeve, the window metal sleeve being provided with openings to be aligned with the recesses in the resilient member. Because of the metallic character of the window metal, the outer metal sleeve must be provided with a lining member of a resilient material to provide for proper sealing between the outer metal sleeve and the window metal sleeve.
Further, for proper functioning of a fluid damped bushing it is necessary to provide a restricted passage between the fluid containing recesses, such passage frequently being referred to as an inertia track. The damping effect of the bushing is determined by the resistance to flow of the inertia track, and this, in turn, depends upon its length and its cross-sectional area. When such an inertia track is formed in the resilient member of the bushing, its damping effect becomes variable, because of the possibility that the track can be distorted by the distortion of the bushing as it undergoes the imposition of loads, and the removal of loads, during its normal service.